Damper



N. PETERS, PHOTO-HTHOGRAFHER, WASHINGYON. U. C,

union.

J. R.V ROBINSON, OF BOSTON, MASSACHUSETTS.

DAIVIPER FOR MULTITUBULAR STEAM-BOILERS.

Specication of Letters Patent No. 31,744, dated March"19, 1861.

To all whom it may concern.'

Be it known that I, J. R. ROBINSON, of Boston, in the county of Suffolk and State of Massachusetts, have invented a new and useful Improvement in Dampers for Multitubular Steam-Boilers; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l is a side view partly in section of a horizontal multitubular boiler, with my invention applied. Fig. 2 is a rear end view of the same. Fig. 3 is a vertical section of the rear tube sheet and damper exhibiting th'e latter in different conditions from Fig. l.

Similar letters of reference indicate correspending parts in the several figures.

In horizontal multitubular boilers there is a natural tendency of the gases of combustion to come out from the upper tubes at a temperature higher than from the lower ones, not alone because of astronger draft through the upper ones, but because while the lower ones are in solid water the upper ones are in foam; and the consequence is vthat much heat is usually lost through the upper tubes. i

The object of my invention is to obviate the effect of the above mentioned tendency, and to this end it consists in a certain construction of and mode of applying a damper in relation to the rear tube sheet of such a boiler, whereby I am enabled to control the draft through the several tubes.

'Io enable others skilled in the art to make and use my invention I will proceed to describe itsconstruction and operation.

A. is the shell of the boiler; a, a, the hori zontal tubes; and B. the rear tube sheet. The smoke box in rear of the sheet B. into which the tubes discharge is not represented in the drawing.

C D. is the damper made in two parts, of which the part C. is of a form to cover the mouths of the upper tiers of tubes, say about half, or more or less, of the`whole number and the part D. is of a form to cover the re- I mainder. The upper edge of the upper part C., which occupies a horizontal position, is attached by hinges Z), b, close to the tube sheet B. and the upper edge of D. is hinged by hinges o, c, to the lower edge of C. the axis of the hinges c, 0, being horizontal and parallel with the axis of the hinges o, o.

E. is a shaft which serves as a pin to the hinges Z), Z9, but is fitted to turn on its axis independently of the damper. This shaft has secured to it, at the middle of its length, a long arm cl, which passes down outside of the damper through a long staple e, secured to the part C. near the lower `edge thereof, and through a short staple j', secured to the part D, near the bottom thereof; and

the said `shaft has formed upon or secured to one end of it, an arm g, which is connected by a rod z, with a hand-lever F. conveniently arranged, near the front end of the boiler, to be within the command of the engineer; and suitable means are employed in connection with this hand-lever to secure it in any desirable position. The long staple e, has a number of holes in its sides, at different distances from the damper, for the reception of a pin 71, which is inserted through the said staple outside of the arm g,' and a spring 7c, is applied between the arm g, and part C. of the damper in such manner as to exert a tendency to throw back the said arm from the said part C. The short'staple is only just long enough to permit the arm e, to work freely within it.

The damper is opened and closed by moving the lever F. which operates the shaft E. and its arm d. Its arrangement to swing from its upper edge, causes it, in every position below a horizontal one, to leave the space, between itself and the mouths of the tubes, wider at the lower tubes than at the upper ones, thus' providing for a freer exit of the gas from the lower than from the upper tubes and so counteracting, in a greater or less degree, the natural tendency lto a stronger draft through the upper tubes. In opening the damper, supposing it to have been quite closed, as shown in black outline in Fig. 3, the spring 7c, between the arm d,

and the upper part C. of the damper keeps t-he said part C. closed while the part D. opens, as shown in red oiitline in the same figure, until the arm (Z, comes against the pin z', (or against the end ofthe staple e, if the pin i, is omitted) when the arm opens the part C, also as shown in Fig. l, but keeps the latter part, at a more acute angle to the tube sheet so that all the tubes to which that part belongs, continue to have the exit of the gases from them obstructed in more than a gradually increasing ratio from the bottom of the damper.

It will be understood by reference to Fig. l that the tubes covered by C. may be kept entirely closed, while those covered by D. have a narrower opening according to their elevation. In closing the damper, the part C. is closed before any movement on the hinges c, c, takes place. The relative movements of C. and D. are controlled by the position of the pin z'. The farther from the damper the said pin is placed, the less will be the opening of C. relatively to D. and if the pin is removed altogether so that the arm d, has to come against the end of the staple e, before it can open C. the relative opening of C. will be still less. The pin z', may however be so placed that the parts C. and D. mayobe brought into the same plane and be made to move as though they were parts of the same plate without any joint at c, c.

Instead of the damper being composed of two parts or sections C. D. it may be made of three or four applied in the same manner, the upper one always having a longer staple for the arm CZ, to pass through than the one below it.

That I claim as my invention and desire u to secure by Letters Patent is,

The damper constructed of two or more parts hinged together and arranged relatively to the tubes of the boiler substantially as herein described, and combined by such a syst-em of connections as will make the lower parts capable of opening before or independently of the upper ones, substantially as and for the purpose herein described.

J. R. ROBINSON. Vitnesses z JONA LADD, GEO. L. BURTWELL. 

